Optically sensitized light-sensitive silver halide material

ABSTRACT

following formulae:   wherein Q and Q&#39;&#39;&#39;&#39; represent sulfur or selenium; Y stands for hydrogen, a dioxy methylene or a fused-on benzene ring or one or more substituents selected from halogen, alkyl, alkoxy and alkylthio; R represents alkyl having up to 3 carbon atoms; R&#39;&#39;&#39;&#39; and R&#39;&#39;&#39;&#39; represent alkyl, sulfo substituted alkyl, sulfato substituted alkyl, carboxy substituted alkyl, hydroxyl substituted alkyl or alkyl substituted by -SO2-NH-CO-alkyl or CO-NH-SO2-alkyl; Z stands for hydrogen, alkyl with up to 3 carbon atoms, alkyoxy or a fused-on benzene ring; A and B represent hydrogen, halogen, alkyl, alkoxy, alkylthio, a fused-on benzene ring or a dioxy methylene group; and X is an anion where the remainder of the dye has a net positive charge.

United States Patent Johannes Gbtze Bergisch-Neukirchen;

Oskar Riester, Leverkusen, Germany; Herman Adelbert Philippaerts, Mortsel; Theoiiel Hubert Ghys, Kontich, Belgium; Marie Hase, Schildgenbergisch-Gladbach; Karl Kiiffner, Unterhaching b. near [72] Inventors Aug. 24, 1967, Germany, 56 590 [54] OPTICALLY SENSITIZED LIGHT-SENSITIVE SILVER HALIDE MATERIAL 8 Claims, 3 Drawing Figs.

52' US. Cl 96/124, 96/ l 09 511 lm. Cl G03c 1/28 [50] Field of Search ..96/l04, 109

[56] References Cited UNITED STATES PATENTS 2,430,072 11/1947 Nicholson et al. 96/104 3,432,303 3/1969 Jones et al. 96/104 Primary Examiner-J. Travis Brown AttorneyConnolly and Hum ABSTRACT: Silver halide emulsions are very effectively sensitized to red with combination of two dyes OPTICALLY SENSITIZED LIGHT-SENSITIVE SILVER HALIDE MATERIAL It has been known for a long time that the sensitivity of light-sensitive layers, especially silver halide-emulsion layers, may be increased by adding substances which increase their range of spectral sensitivity. Numerous substances which mainly belong to the class of cyanine dyes have been described for so sensitizing silver halide emulsion layers.

The sensitization of silver halide emulsion layers in the far red region between about 700850 millimicrons gives rise to special difficulties. Various sensitizing dyes have been described for this spectral region, e.g. tetramethine merocyanines, rhodacyanines, pentamethine dyes and certain groups of carbocyanines. All dyes of these groups have serious disadvantages when used for sensitizinghighly sensitive silver iodobromide emulsions.

Tetramethine merocyanines and rhodacyanines are suitable mainly for sensitizing silver chloride or bromide emulsions that contain color couplers but not for silver iodobromide emulsions of maximum sensitivity. The sensitivities achieved with these compounds are unsatisfactory when compared with the intensity of panchromatic sensitization nowadays achieved with highly sensitive materials in the region of 65010 690 millimicrons.

Apart from their insufficient sensitizing action and storage stability, pentamethine dyes show incompatibility with other sensitization dyes for shorter wavelength. I

Trimethine cyanines that have at least one quinoline nucleus have an absorption maximum at about 580 millimicrons and a sensitization maximum at 610 millimicrons. By introducing 'substituents in the meso position of the trimethine chain the sensitization maxima of these dyes are shifted to wavelengths above 700 millimicrons. N-methyl-' benzothiazole-N-methylquinoline trimethine cyanine substituted by an ethyl group in the meso position has an extraordinary maximum of 730 millimicrons. This .phenomenon can be observed in a large number of meso-alkyl-substituted asymmetrical thioand selnoguinocarbocyanines, especially in those derived from 5,6-henzoquinoline. Nevertheless, these and similar dyes are of limited utility either because they cause fogging of the silver halide emulsion and because'the sensitizing activity is insufficient, or because the spectral sensitivity does not extend uniformly over the visible and far red region of the spectrum which is desirable for certain applications.

The object of this invention is to provide'substituents sensitized silver halide emulsion layer the sensitivity of which extends up to thefar red region of the spectrum.

We now have found that photographic silver-halide emulsions can be sensitized to maximum sensitivity in the farred region of the spectrum by applying a mixture of twotypes of sensitizing dyes. The first group of these sensitizing dyes comprises dyes of the following formula:

Q R f 2 Y o-oH=c-c I in which 0 represents sulfur or selenium;

' benzene ring or oneor more of alkyl, alkoxy, or alkylthio, the

alkyl groups of which have preferably up to 5 carbon atoms, or halogen such as-chlorine, bromine or iodine.

R represents alkyl with up to 3 carbon atoms;

R and R" stands for alkyl including substituted alkyl, e.g., alkyl with 1 to 4 carbon atoms substituted in the ,8-, yor 0)- position by a hydroxyl group, a sulfo group, a sulfato group, a carboxyl group, a CO-NH-SO -alkyl group or an -SO -NH- CO-alkyl group in acid or salt form such as the alkali metal or ammonium salt, e.g. the sodium salt or trimethylammonium salt;

X denotes any anion, e.g. bromide, iodide or methyl sulfate, or does not exist 'when R or 'R" itself contains an anionic p;

2 represents hydrogen, 'alkyl with up to 3 carbon atoms, preferably methyl, alkoxy or a fused-on benzene ring.

The above quinoline dyes areapplied in combination with selenoor thiocarbocyanines of the following formula:

Q,'R,R; R" and X'have the same meanings as above.

A and B represent hydrogen, a fused-on benezene ring, preferably in the 4.5-position, a dioxymethylene group, preferably in the 5.6-position or one or more of: alkyl, alkoxy, or alkylthio, the alkyl groups of which having preferably up to 5 carbon atoms, or halogen such as chlorine, bromine or iodine; and

Q stands for sulfur or selenium.

The dyes of formula I have an extraordinary maximum above 700 millimicrons and are completely compatible with the dyes of formula ll. The tendency of dyes of formula I to cause fogging isnow surprisingly practically completely suppressed (particularly in high-sensitive silver halide emulsions) by combining them with sensitizing dyes of formula II, and, in addition, a considerable increase in the sensitizing effect in the deep red region is achieved. This was all the more unexpected since dyes of group ll normally only sensitize below 700 mil- I limicrons, when used alone. R Particular utility is exhibited by combining dyes of the fol- R' X lowing formulae:

Sensitization maximum in Dyes of Formula I millimicrons The preparation of photographic silver halide emulsions substantially comprises three steps:

1. Precipitation of the silver halide in the presence of a protective colloid and physical ripening.

2. Removal from the emulsion of excess water-soluble salts introduced during precipitation, generally by washing, and

3. Chemical ripening or after-ripening, which serves to impart the desired sensitivity to the emulsion.

The sensitizing dyes according to the present invention can be used in any silver halide emulsions. Suitable silver halides are silver chloride, silver bromide or mixtures thereof, if desired containing a small amount of silver iodide up to lmols percent. The silver halides may be dispersed in the usual hydrophilic compounds, for example, carboxymethylcellulose, polyvinyl alcohol, polyvinyl pyrrolidone, alginic acid and its salts, esters or amides or preferably gelatin.

The sensitizing dyes to be used according to the present invention are advantageously added to the photographic emulsion before the chemical ripening or before casting. The methods employed for this are generally known to persons skilled in this art. The sensitizing dyes are generally incorporated in the emulsion in the form of solutions, e.g., in alcohol or mixtures of alcohol and water. The solvents must, of course, be compatible with gelatin and must not have any adverse effects on the photographic properties of the emulsion. Water, methanol or mixtures thereof are generally used as so]- vents. The quantity of sensitizing dye added may vary within wide limits, e.g., between 2 and 200 mg. preferably between and 100 mg. per kg. of the silver halide emulsion. The concentration of dye may be adapted to the particular requirements, depending on the type of emulsion, the desired sensitizing effect etc. The most suitable concentration for any given emulsion can easily be determined by the usual tests employed in the art of emulsion making.

The emulsions may also contain chemical sensitizers, e.g., reducing agents such as stannous salts, polyamines such as diethylentriamine, or sulfur compounds as described in US. Pat. No. 1,574,944. Furthermore, salts of noble metals, such as ruthenium, rhodium, palladium, iridium, platinum or gold may be contained in the emulsions for chemical sensitization, as described in the article by R. Koslowsky, Z.wiss.Pot. 46, 65-72 (1951). The emulsions may also contain, as chemical sensitizers, polyalkylene oxides, especially polyethylene oxide and derivatives thereof.

The emulsions may be hardened in the usual manner, for example, with formaldehyde or by use of halogen-substituted aldehydes which contain a carboxyl group, e.g., mucobromic acid, diketones, methanesulfonic acid esters and dialdehydes.

EXAMPLE 1 A highly sensitive silver bromide gelatine emulsion containing 3 mols percent OF silver iodide, and the usual additives such as 0.35 g. of saponin as wetting agent, 5 ml. of a percent aqueous formaldehyde solution as hardener and 300 mg. of l,3,3a,7-tetraaza-4-hydroxyl-6 methylindene as a stabilizer, is divided into several parts.

To the separate parts are added, per kg., the quantities of sensitizing dyes shown in the following table 1. The emulsions are then applied onto a cellulose triacetate support in the usual manner and dried.

The layers obtained are exposed in a conventional sensitometer behind a step wedge with a rise of 2 behind a red filter.

The exposed samples are developed and fixed in the usual manner. The sensitometric results are shown in the following table 1. The relative sensitivities are indicated by the number of measurable steps of the wedge.

TABLE 1 sensitizing dyes Dyes of of formula I formula II Expen- Quan- Quan- Relative ment tity mg. No tity mg No. sensitivity Fog.

45 I/3 12 Fog. 30 I/3 15 II/l 14 Clear 45 U2 11 Fog. 30 U2 15 11/1 13 Clear. 45 Ill 11 Fog. 30 Ill 15 11/1 16 Clear. 45 II8 17 0.24. 30 I/S 15 11/1 20 0.12. 45 U6 13 0.32. 30 I/6 15 11/1 17 0.26. 30 I/6 30 11/1 18 0.23. 45 U5 19 0.44. 30 H5 15 11/3 22 0.18. 30 U5 15 11/4 21 Clear. 30 U5 15 11/1 22 Do. 30 U5 15 11/5 21 Do. 45 I/4 8 0.62. 45 1 4 30 11 1 15 0.34. 45 II8 20 0.27. 30 US 15 11/5 21 0.11. 30 IIS 15 II/G 22 0.12. 45 U6 12 0.45. 30 II6 30 II/7 15 0.28. 45 II10 14 0.40. 30 I/lO 15 11/1 18 0.23.

The sensitograms of experiments 3 and 4, l2 and 16, and 24 and 25 are shown in Figures 1 to 3 respectively. In the graphs, the intensity of sensitization is plotted as the axis of ordinates against the wavelengths as the axis of abscissae. The full line curves in the three pairs of experiment represents the sensitization of the deep red sensitization of dyes of formula I alone, and the broken line curves represent the sensitization of the combination according to the invention.

The above experiments demonstrate that fogging caused by dyes of formula I is reduced and, in addition, a considerable increase in sensitivity is achieved. The sensitization maxima of the sensitization dyes of formula l are shifted hypsochromically by up to about 20 millimicrons when used in combination with dyes of formula II Example 2 A silver iodobromide emulsion of medium sensitivity containing 47 mols percent of silver iodide and the usual additives described in example 1 is divided into several portions.

sensitizing dyes in the amounts per kg. indicated in the following table are added to the individual portions which contain 0.3 mols of silver halide per kg. The emulsions are then applied on a cellulose triacetate support in the usual manner and dried. A

The layers obtained are exposed in a conventional sensitometer behind a step wedge of constant 0.15, once without filter (general sensitivity) and once behind a yellow filter (spectral sensitization sensitivity).

The transmission of the yellow filter for light 0.1 a wavelength shorter than 495 millimicrons is less than 0.1 percent; for light having a wavelength of 550 millimicrons and longer the transmission is higher than 90 percent.

The exposed samples are developed and fixed in the usual manner. The sensitometric results are shown in'table 2 below.

of the wedge.

TABLE 2 sensitizing dyes Formula I Formula II Sensitivity Sensitization Amount, Amount, maximum, Experiment No. mg. No. mg. General Spectral Fog my 1.0 18 0.28 1.1.. 20 19 18 0.30 730 1.2-- 20 II/8 20 20 20 0. 30 730 2.0. 16. 0. 24 2.1- 20 19 18 0.27 730 2.2- 20 11/9 20 21 21 0.30 730 3.0. 18 5 0. 22 3.1. 20 19 18 0. 34 730 3.2. 20 II/ 10 20 21 21 0. 30 730 3.3. 20 11/15 20 21. 5 20 0. 30 730 3.4- 20 11/12 20 21 21 0. 27 730 4.0. 14 2 0. 18 4.1. 30 18 17. 5 0. 27 725 4.2.. 15 11/1 15 18. 5 18 0. 22 720 4.3 I/8 11/1 10 19 18. 5 0.22 720 EXAMPLE3 20 then applied onto a cellulose trlacetate support in the usual Further processing was accomplished as described in example 2. The sensitometric results are shown in the following table 3.

manner and dried.

Further processing was accomplished as described in example 2, with the difference, however, that now there is used a yellow filter whose transmission of light having a wavelength shorter than 460 millimicrons is less than 0.1 percent and the transmission of which for light having a wavelength of 520 millimicrons and longer is higher than 90 percent. The sensitometric results are shown in the following table 4.

TABLE 3 sensitizing dyes Formula I Formula II Sensitivity Sensitization Amount, Amount, maximum Experiment N 0. mg. 0. mg. General Spectral Fog my Example4 A'vr iee lsion f ed n"vit v s11 e hald mu 0 m rum se sin y ha mg the EXAMPLES following composition:

88.4 mol percent of silver bromide 25 mol percent of silver iodide 9 mol percent of silver chloride, and containing 0.3 mol of silver halide per kg., is divided into several portions. Sensitizing dyes in amounts per kg. shown in the following table 4 are added to the individual samples. The emulsions are Several samples of the emulsion of example 4 and sensitized with the dyes shown in the following table are processed as described in example 2 to compare the general sensitivity and the spectral sensitization sensitivity with the difference, however, that a yellow filter is used as described in example 4. The

sensitometric results are shown in the following table 5.

' TAB LE 5 sensitizing dyes Formula I Formula II Sensitivity Sensitization Amount, Amount, maximum, Experiment N 0. mg. N mg General Spectral Fog my We claim: 3. The emulsion of claim 1, wherein the sensitizing dyes 1. A silver halide emulsion sensitized to red by sensitizing have the following formulae:

amounts of at least one sensitizing dye of each of the following formulae: m

I Q s I Z on; r Y I c=oH-c=crr N \(I-G) Iii IIQ' (CHQQSOQF) X- t 02m and H Q Q, Se Se R CH (IJZHS 0CH:|

30 COH=CCH=C A C-OH- CHC B CH CH 3- a N f Iii K- II! C2H5 Br CzHs 4. The emulsion of claim 1, wherein the sensitizing dyes have the following formulae: wherein Q and Q" represent 'sulfur or selenium;

Y stands for hydrogen, a dioxy methylene or a fused-on 40 I benzene ring or one or more substituents selected from halogen, alkyl, alkoxy and alkylthio;

R represents alkyl having up to 3 carbon atoms; CH; R" and R" represent alkyl, sulfo substituted alkyl, sulfato I \m substituted alkyl, carboxy substituted alkyl, hydroxyl sub- N stituted alkyl or alkyl substituted by -SO -NH-CO-alkyl or \N (Him- 01 CO-NH-S0 -alkyl; 2 stands for hydrogen, alkyl with up to 3 carbon atoms, aland kyoxy or a fused-on benzene ring; Se 8 A and B represent hydrogen, halogen, alkyl, alkoxy, al- (71115 kylthio, a fused-on benzene ring or a dioxy methylene c=cH0=c --0 group; and CH 0 CH; X is an anion where the remainder of the dye has a net posi- N f tive charge. (CH hS 0am (CHg)3S03 2. The emulsion of claim 1, wherein the sensitizing dyes have the following formulae: 5. The emulsion of claim 1, wherein the sensitizing dyes have the following formulae:

6 The emulsion of claim 1, wherein the sensitizing dyes have the following formulae:

8. The emulsion of claim 1, which contains a stabilizing 7. The emulsion of claim 1, wherein the sensitizing dyes quantity of a hydroxylor amino substituted tetraor penhave the following formulae: taazaindene stabilizer.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3.615634 Dated Oct. 26. 1971 Inventor(5) Johannes Gotze et a1 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 39, "Belnoguinocarbocyeninee" should read selenoquinocarbocyanines Column 1, line 40, "henzoquinoline" should read benzoquinoline Column 1, line 46, "substituents" should be optically Column 2, formula 1/1, the left hand ring system should read Column 3, formula 1/2, the left hand ring system should read Column 6, dyes 1/11 and I/l2, the sensitization maximum figures to the right of the formulae, should read 715 720 respectively. Column 6, formula 1/12, the right hand ring system should read Patent No. 3,615,634 Dated Oct. 26, 1971 Inventor(s) Johannes Gotze et a1 P 2 Claim 1, column 19, lines 47 and &8, "alkyoxy" should read alkoxy Claim 2, column 19, last formula, should read Signed and sealed this 1st day of August 1972.

(SEAL) Attest:

EDWARD M.F'LETCHER,JR. ROBERT GOTTSCHALK Attasting Officer Commissioner of Patents 

2. The emulsion of claim 1, wherein the sensitizing dyes have the following formulae:
 3. The emulsion of claim 1, wherein the sensitizing dyes have the following formulae:
 4. The emulsion of claim 1, wherein the sensitizing dyes have the following formulae:
 5. The emulsion of claim 1, wherein the sensitizing dyes have the following formulae:
 6. The emulsion of claim 1, wherein the sensitizing dyes have the following formulae:
 7. The emulsion of claim 1, wherein the sensitizing dyes have the following formulae:
 8. The emulsion of claim 1, which contains a stabilizing quantity of a hydroxyl- or amino substituted tetra- or pentaazaindene stabilizer. 